1. Field of the Invention
The present invention relates to a method of manufacturing an optical compensation sheet and the optical compensation sheet, and more particularly, to a method of manufacturing an optical compensation sheet composed of an orientation layer formed on a substrate and a liquid crystal layer formed on the orientation layer, and to the optical compensation sheet.
2. Related Art
A liquid crystal display device is constituted of liquid crystal cells, polarizing elements and an optical compensation sheet (phase difference board). The optical compensation sheet is used for eliminating coloring of images and enlarging a viewing angle. As the optical compensation sheet, a drawn polymer film has been used up to present. However, in recent years, it has been proposed to use an optical compensation sheet having an optical anisotropic layer formed of liquid crystal molecules on a transparent substrate, in place of the drawn polymer film.
Such an optical compensation sheet is manufactured by coating an oriented layer on the surface of a long polymer sheet while feeding the polymer sheet continuously, dehydrating it, applying rubbing treatment onto the surface of the oriented layer, and applying a solution of a liquid crystal compound in an organic solvent onto the oriented layer (see Japanese Patent Application Laid Open No. 2003-329833). The optical compensation sheet thus manufactured is shipped and delivered to a manufacturer, and then, subjected to saponification and processed into a polarizing plate. The saponification for polarizing plate is performed by using a saponification liquid such as sodium hydroxide having a concentration of 5 to 20% by weight at a temperature of about 25 to 80° C. (see Japanese Patent Application Laid Open No. 2002-267839).